1. Field of the Invention
The present invention relates to a wired circuit board. More particularly, the present invention relates to a wired circuit board such as a suspension board with circuit.
2. Description of Related Art
A suspension board with circuit used in a hard disk drive is a wired circuit board formed with a wired circuit pattern on a suspension board which supports a magnetic head via an insulating layer. In recent years, this suspension board with circuit has become widely available because a magnetic head keeps a minute gap from a magnetic disk against an airflow caused when the magnetic head and the magnetic disk travel relatively to each other, so that the magnetic head obtains a good floating posture.
Such suspension board with circuit is formed with a gimbal portion, wherein the gimbal portion include comprising a tongue portion for mounting a slider equipped with a magnetic head, and an outrigger portion arranged on both widthwise sides of the tongue portion and formed with a wired circuit pattern usually at a tip portion thereof. The rigidity of the outrigger portion is an important factor in order to precisely adjust a floating posture (angle) of the slider with respect to the magnetic disk.
Meanwhile, in recent years, there has been a need for a signal having a higher frequency in the suspension board with circuit from a viewpoint of a higher density data. However, the higher frequency causes higher transmission loss in a conductive pattern.
Therefore, a proposal has been made that transmission loss in a conductor is reduced, for example, by sequentially laminating a lower conductor, an insulating layer, and a conductor consisting of a record-side line and a reproduction-side line on a suspension (cf., Japanese Unexamined Patent Publication No. 2005-11387).